An infrared motion sensor (also known as “a human infrared sensor”) is a passive infrared sensor (PIR) that absorbs an infrared radiation signal from an external object through a Fresnel lens on the surface of the sensor itself and generates an analog signal with positive and negative oscillations. The existing technique is to sample such analog signal so as to convert the infrared radiation signal to an infrared radiation magnitude and then compare such magnitude with a preset threshold to determine whether any object is nearby.
However, infrared radiation magnitudes of humans, animals, and other objects would be different, and infrared radiation magnitudes measured under different ambient conditions would also be different. Hence, a single fixed threshold and a single determination approach used in the existing technique would cause false alarms due to the above differentiations.